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Driveway sealants may be hazard

The trouble with coal tar

Products made with coal tar contain polyaromatic hydrocarbons, a family of 100 carbon- and hydrogen-based chemicals formed by burning coal. The Centers for Disease Control and Prevention lists 17 compounds and chemicals it considers as health hazards.

COAL-TAR-BASED SEALANTS
Refined coal tar is removed from coke ovens and used as the base liquid in sealants that many homeowners and businesses spread on asphalt driveways and parking lots. The sealants fill in cracks, reduce erosion from storm water and extend the life of asphalt pavement.

Studies suggest that parking lots and driveways covered with coal-tarbased sealants are a prime source of high PAH concentrations that end up in streams, lakes and dust in buildings, including houses.

ASPHALT-BASED SEALANTS
These sealants use a petroleum-based liquid from oil refineries that is similar to the liquid used to create the asphalt in driveways and roads. Studies have found low levels of PAH in these sealants.

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It's been tough to even find an asphalt driveway these days under all the snow, let alone think
about sealing one. But before long, thousands of central Ohio homeowners will spend hot, sunny days
spreading fresh layers of thick, black sealant on their driveways.

These sealants, used for more than 50 years to help keep asphalt from cracking and crumbling,
now face increasing scrutiny from federal environmental officials.

Recent studies of sealants made with coal tar show that the substances can contain high
concentrations of toxic compounds called polyaromatic hydrocarbons, or PAH.

The compounds are washed into streams and carried into our houses in tiny particles of sealant
that break off under the weight of car tires and snow shovels and in rainwater.

A 2009 U.S. Geological Survey study of apartments in Austin, Texas, found that PAH in household
dust was 25 times higher if the parking lots outside were covered in coal-tar sealants.

"It's eye-opening," said Barbara Mahler, a hydrologist with the U.S. Geological Survey and
author of the study that appeared in January in the journal Environmental Science and
Technology.

Mahler said the study raises concerns that infants and toddlers might ingest dust laden with
PAH.

Past studies that Mahler performed linking PAH "hot spots" in streams to nearby parking lots led
Austin city officials to ban coal-tar sealants in 2006. Coal-tar bans were adopted in Dane County,
Wis., in 2007 and in Washington, D.C., in 2009.

No limits have been set on coal-tar sealants in Ohio. The U.S. Environmental Protection Agency
is conducting its own study of PAH in storm-water runoff from parking lots. Results should be
available in September, said agency spokeswoman Enesta Jones.

Industry officials say their products are safe and dispute Mahler's findings. Anne LeHuray,
director of the Pavement Coatings Technology Council in Alexandria, Va., said the research unfairly
singles out sealants.

PAH is released whenever carbon is burned. The compounds are produced by cars, trucks,
fireplaces, grills and cigarettes, among other things.

"Nobody is saying there is no contribution to PAH (in the environment) from coal-tar-based
sealant," LeHuray said. "We're saying our contribution relative to all these other sources is
insignificant."

Coal tar is a byproduct of coke ovens used in making steel. The tar is refined and used as the "
base" liquid in pavement sealants.

It's unclear how much coal-tar sealant is produced each year. U.S. Department of Energy data
show that Ohio coke ovens produced about 16.5 million gallons of crude tar in 2007, the most recent
data available.

There also are petroleum-based sealants, which contain no coal tar. STAR Inc., a Columbus
company with 17 factories in the U.S. and China, makes several sealants that use either coal tar or
petroleum.

STAR Inc. officials declined to comment.

Mahler's tests of the different sealants show that polyaromatic hydrocarbons make up about 0.7
percent of petroleum-based sealant and as much as 20 percent of coal-tar sealants.

Polyaromatic hydrocarbons are toxic to fish. Seventeen of the compounds are deemed hazardous for
humans, including seven that the U.S. EPA considers potential cancer threats.

Chip Brewer, owner of the Brewer Co., a sealant manufacturer in Milford, in southern Ohio, said
more research is needed to prove whether coal-tar sealants are health hazards.

"We believe that there's been a rush to judgment," Brewer said.

Mahler said she's certain that coal-tar sealants are the prime source of PAH in streams and
apartments she surveyed.